1. Field of the Invention
The present invention relates to surgical instruments for applying surgical fasteners or staples to body tissue, and more particularly to an apparatus for applying an annular array of surgical staples or fasteners. Still more particularly, the invention relates to an apparatus having an adjustable mechanism for controlling the spacing between the staple pusher member and the anvil member between which the tissue is positioned to effect a circular anastomosis.
2. Discussion of the Related Art
Surgical stapling devices for applying an annular array of staples or fasteners to tissue are well known in the art. These devices typically include means for controlling the spacing between the fastener assembly and the anvil member at the distal end of the apparatus. The fastener assembly generally includes a circular array of fasteners such as staples, anastomosis rings, and the like, while the anvil member includes means for completing the circular anastomosis, typically an array of bucket members that clinch the staples after the staples are expelled from the fastener assembly, or may include a locking member for the anastomosis ring. The means for advancing or retracting the anvil in relation to the fastener assembly typically includes a wing-nut type mechanism at a proximal end of the instrument or a rotatable knob member, both of which engage a worm gear arrangement in the handle mechanism to slowly, and methodically advance the anvil member towards the fastener assembly.
Surgical stapling devices for applying an annular array of staples, as well as devices for completing a surgical anastomosis through the provision of anastomosis rings, are well known in gastric and esophageal surgery, for example in classic or modified gastric reconstruction typically formed in an end to end, end to side, or side to side manner. In use, the instrument is positioned within the lumen of an organ such as the stomach, esophagus, or intestine in order to perform the anastomosis. The tissue is positioned between the anvil and the fastener assembly and is typically tied off, for example, by a purse string suture. Thereafter, the anvil member is advanced towards the fastener assembly by rotation of the rotatable knob or wing nut assembly at the proximal end of the instrument to hold the tissue between the anvil member and the fastener assembly. As the staples or the fasteners are expelled from the fastener assembly, a circular knife typically follows the application of the staples to excise unwanted tissue at the anastomosis site. The instrument is then removed from the lumen of the organ.
Closing mechanisms associated with the prior art stapling or fastening devices typically utilize a complex worm gear arrangement or screw bearing member to open and close the spacing between the anvil and the fastener assembly. These devices generally provide a rotatable knob or wing-like assembly remote from the fastener or staple pusher member, and the worm gear mechanism is provided to translate the rotational movement of the knob into longitudinal movement of the anvil member towards the staple pusher member. In order to effect this movement, the surgeon must grasp the device with one hand while rotating the knob or wing-like assembly with the other hand. Because the worm gear is typically a precision component for moving the anvil member in precise increments, it is a time consuming process to move the anvil member a full distance towards the fastener assembly during the surgical procedure. Typical devices require 15 to 20 full 360.degree. rotations of the knob or wing nut assembly to fully close the instrument in order to fire or expel the staples or fasteners into the tissue.
It would be advantageous to expedite the surgical procedure utilizing circular anastomosis instruments. Additionally, although many prior art devices are provided with a visual indicator to signal the surgeon when the anvil has reached a firing position adjacent the staple or fastener assembly, there is generally no indication of the position of the anvil member in relation to the staple assembly until the anvil is immediately adjacent the fastener or staple assembly.
The novel surgical stapling or fastening device for performing a circular anastomosis procedure of the present invention provides an instrument having an adjustable closure mechanism for controlling the spacing between the anvil member and the fastener assembly positioned at the distal end of the instrument. The closing mechanism of the present invention provides a mechanism for both rapidly approximating the distance between the anvil and the fastener assembly, and for incrementally adjusting the remaining distance after the initial rotation. The instrument of the present invention provides a quick and efficient means for approximating the anvil and fastener assembly while including means for accurately positioning the anvil in relation to the fastener assembly to properly set the distance for applying staples or fasteners to the tissue. In addition, the instrument of the present invention allows the surgeon to rapidly move the anvil towards the fastener assembly in a minimal amount of turns so that the surgeon has an indication of the location of the anvil member in relation to the fastener assembly at all times during rotation of the grip member at the handle of the instrument.